The present invention relates to an image scanning apparatus, image forming apparatus, image forming system, image scanning control method, and storage medium and, more particularly, to an image scanning apparatus which can make generation of a black stripe image due to dust harder when sheetfed scans are made using a combination of a linear image sensor and an automatic document feeder attached to the image scanning apparatus, an image forming apparatus, an image forming system, an image scanning control method, and a storage medium.
Conventionally, an image scanning apparatus with a linear image sensor has an arrangement shown in, e.g., FIG. 13. FIG. 13 is a block diagram showing an example of the arrangement of a conventional image scanning apparatus. Referring to FIG. 13, reference numeral 101 denotes a document illumination lamp; 102 to 104, first to third mirrors; 105, a lens; 106, a linear image sensor; 107, a platen glass; 108, a document; 109, a white plate serving as a reference for shading correction; and 110, a dummy glass. The image scanning apparatus shown in FIG. 13 can two-dimensionally scan the document 108 by moving (sub-scanning) the first to third mirrors 102 to 104 and the document illumination lamp 101 in the direction of an arrow.
FIG. 14 is a block diagram showing an example of the arrangement when an automatic document feeder is attached to the conventional image scanning apparatus shown in FIG. 13. An automatic document feeder 200 comprises an automatic document feeding conveyor belt 202, driving roller 203, and document loader 204, and conveys a document 201 loaded on the document loader 204 by rotating the automatic document feeding conveyor belt 202 by the driving roller 203.
As an image scanning mode that uses the aforementioned image scanning apparatus and automatic document feeder, a xe2x80x9csheetfed scanningxe2x80x9d mode is known. In the xe2x80x9csheetfed scanning modexe2x80x9d, the image scanning apparatus moves the mirrors to scan a predetermined position of the platen glass, and the automatic document feeder moves a document at a given speed in that state, thereby scanning an image of the document. That position on the platen glass which is scanned by the image scanning apparatus is called a xe2x80x9csheetfed scanning positionxe2x80x9d, and is constant, as indicated by the broken line in FIG. 15. On the other hand, the automatic document feeder moves a document in the direction of an arrow in FIG. 15. In this sheetfed scanning mode, since the document need only be moved in a given direction, the time interval required between neighboring documents upon successively scanning a large number of documents is shorter than that required in the normal scan.
However, the aforementioned prior art suffers the following problem. That is, in the sheetfed scanning mode, if dust, soil, or the like is present on a portion of the platen glass, as shown in FIG. 15, a black stripe forms at the corresponding main scan position of the scanned image. However, as a conventional method of preventing a black stripe from forming, the platen glass surface can only be cleaned.
The present invention has been proposed to solve the conventional problems, and has as its object to provide an image scanning apparatus which detects generation of a black stripe formed due to dust, soil, or the like on a platen glass in the sheetfed scanning mode, and makes control for changing the sheetfed scanning position or displays a warning indicating that dust or soil is attached to the platen glass in accordance with the detection result, thus reducing the frequency of occurrence of generation of a black stripe, an image forming apparatus, an image forming system, an image scanning control method, and a storage medium.
In order to achieve the above object, an image scanning apparatus for scanning an image while moving a document on a platen glass at a constant speed, comprises black stripe image detection means for detecting the presence/absence of generation of a black stripe image on the basis of an image signal obtained by the image scan, and control means for, when the black stripe image detection means detects generation of the black stripe image, determining that dust or soil is attached to a surface of the platen glass, and making control for changing a stop position of an optical system for guiding light reflected by the document to an image scanning system in the image scan.
According to a preferred aspect of the present invention, the apparatus further comprises document moving means for moving the document on the platen glass in a sub-scan direction at a constant speed, optical system moving means for moving/stopping a mirror table, that supports a reflected light guide mirror as the optical system, to scan a predetermined position on the platen glass, document illumination means for illuminating the document, that moves along the surface of the platen glass, at a stop position of the mirror table, and image scanning means serving as the image scanning system for scanning the image from the document, which moves at the constant speed, at the stop position of the mirror table.
According to a preferred aspect of the present invention, the black stripe image detection means comprises binarization means for binarizing image data scanned by the image scanning means, accumulation means for accumulating the binary data for a predetermined number of lines at N-line intervals (N: an arbitrary integer) in units of pixels, and comparison means for comparing the accumulation result with a predetermined determination level, and determining that a black stripe image is generated at the corresponding pixel position when the accumulation result has exceeded the determination level.
According to a preferred aspect of the present invention, the black stripe image detection means comprises black signal thickening means for selecting and outputting one with a smaller level of signals obtained before and after image data scanned by the image scanning means is delayed by a predetermined number of pixels in a main scan direction, binarization means for binarizing data scanned output from the black signal thickening means, accumulation means for accumulating the binary data for a predetermined number of lines at N-line intervals (N: an arbitrary integer) in units of pixels, and comparison means for comparing the accumulation result with a predetermined determination level, and determining that a black stripe image is generated at the corresponding pixel position when the accumulation result has exceeded the determination level.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection means detects the presence/absence of generation of the black stripe image is set before a document scan by the image scanning means, and the black stripe image detection means detects the presence/absence of generation of the black stripe image using image data scanned at the predetermined position on the platen glass by the image scanning means while moving a belt surface of a document conveyor belt that forms the document moving means by the control means.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection means detects the presence/absence of generation of the black stripe image is set after a document scan by the image scanning means, and the black stripe image detection means detects the presence/absence of generation of the black stripe image using image data scanned at the predetermined position on the platen glass by the image scanning means while moving a belt surface of a document conveyor belt that forms the document moving means by the control means.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection means detects the presence/absence of generation of the black stripe image is set between neighboring documents upon successively scanning documents by the image scanning means, and the black stripe image detection means detects the presence/absence of generation of the black stripe image using image data scanned at the predetermined position on the platen glass by the image scanning means while moving a belt surface of a document conveyor belt that forms the document moving means by the control means.
According to a preferred aspect of the present invention, the apparatus further comprises warning means for generating a warning message indicating that dust or soil is attached to the surface of the platen glass when the black stripe image detection means detects generation of the black stripe image.
In an image forming apparatus which mounts an image scanning apparatus for scanning an image while moving a document on a platen glass at a constant speed, and forms an image on a recording medium such as a recording sheet or the like on the basis of the scanned image, the image scanning apparatus comprises black stripe image detection means for detecting the presence/absence of generation of a black stripe image on the basis of an image signal obtained by the image scan, and control means for, when the black stripe image detection means detects generation of the black stripe image, determining that dust or soil is attached to a surface of the platen glass, and making control for changing a stop position of an optical system for guiding light reflected by the document to an image scanning system in the image scan.
In an image forming system that connects an image forming apparatus which mounts an image scanning apparatus for scanning an image while moving a document on a platen glass at a constant speed, and forms an image on a recording medium such as a recording sheet or the like on the basis of the scanned image, and an external apparatus such as an information processing apparatus or the like, the image scanning apparatus mounted in the image forming apparatus comprises black stripe image detection means for detecting the presence/absence of generation of a black stripe image on the basis of an image signal obtained by the image scan, and control means for, when the black stripe image detection means detects generation of the black stripe image, determining that dust or soil is attached to a surface of the platen glass, and making control for changing a stop position of an optical system for guiding light reflected by the document to an image scanning system in the image scan.
An image scanning control method applied to an image scanning apparatus for scanning an image while moving a document on a platen glass at a constant speed, comprises the black stripe image detection step of detecting the presence/absence of generation of a black stripe image on the basis of an image signal obtained by the image scan, and the control step of, when generation of the black stripe image is detected in the black stripe image detection step, determining that dust or soil is attached to a surface of the platen glass, and making control for changing a stop position of an optical system for guiding light reflected by the document to an image scanning system in the image scan.
According to a preferred aspect of the present invention, the method further comprises the document moving step of moving the document on the platen glass in a sub-scan direction at a constant speed, the optical system moving step of moving/stopping a mirror table, that supports a reflected light guide mirror as the optical system, to scan a predetermined position on the platen glass, the document illumination step of illuminating the document, that moves along the surface of the platen glass, at a stop position of the mirror table, and the image scanning step of scanning the image by the image scanning system from the document, which moves at the constant speed, at the stop position of the mirror table.
According to a preferred aspect of the present invention, the black stripe image detection step comprises the binarization step of binarizing image data scanned in the image scanning step, the accumulation step of accumulating the binary data for a predetermined number of lines at N-line intervals (N: an arbitrary integer) in units of pixels, and the comparison step of comparing the accumulation result with a predetermined determination level, and determining that a black stripe image is generated at the corresponding pixel position when the accumulation result has exceeded the determination level.
According to a preferred aspect of the present invention, the black stripe image detection step comprises the black signal thickening step of selecting and outputting one with a smaller level of signals obtained before and after image data scanned in the image scanning step is delayed by a predetermined number of pixels in a main scan direction, the binarization step of binarizing data output from the black signal thickening step, the accumulation step of accumulating the binary data for a predetermined number of lines at N-line intervals (N: an arbitrary integer) in units of pixels, and the comparison step of comparing the accumulation result with a predetermined determination level, and determining that a black stripe image is generated at the corresponding pixel position when the accumulation result has exceeded the determination level.
According to a preferred aspect of the present invention, a timing at which the presence/absence of generation of the black stripe image is detected in the black stripe image detection step is set before a document scan in the image scanning step, and the presence/absence of generation of the black stripe image is detected in the black stripe image detection step using image data scanned at the predetermined position on the platen glass in the image scanning step while moving a belt surface of a document conveyor belt used in the document moving step in the control step.
According to a preferred aspect of the present invention, a timing at which the presence/absence of generation of the black stripe image is detected in the black stripe image detection step is set after a document scan in the image scanning step, and the presence/absence of generation of the black stripe image is detected in the black stripe image detection step using image data scanned at the predetermined position on the platen glass in the image scanning step while moving a belt surface of a document conveyor belt used in the document moving step in the control step.
According to a preferred aspect of the present invention, a timing at which the presence/absence of generation of the black stripe image is detected in the black stripe image detection step is set between neighboring documents upon successively scanning documents in the image scanning step, and the presence/absence of generation of the black stripe image is detected in the black stripe image detection step using image data scanned at the predetermined position on the platen glass in the image scanning step while moving a belt surface of a document conveyor belt used in the document moving step in the control step.
According to a preferred aspect of the present invention, the method further comprises the warning step of generating a warning message indicating that dust or soil is attached to the surface of the platen glass when generation of the black stripe image is detected in the black stripe image detection step.
In a computer readable storage medium which stores a program module for executing an image scanning control method applied to an image scanning apparatus for scanning an image while moving a document on a platen glass at a constant speed, the program module comprises a black stripe image detection module for controlling to detect the presence/absence of generation of a black stripe image on the basis of an image signal obtained by the image scan, and a control module for, when generation of the black stripe image is detected by the black stripe image detection module, determining that dust or soil is attached to a surface of the platen glass, and controlling to change a stop position of an optical system for guiding light reflected by the document to an image scanning system in the image scan.
According to a preferred aspect of the present invention, the program module further comprises a document moving module for controlling to move the document on the platen glass in a sub-scan direction at a constant speed, an optical system moving module for controlling to move/stop a mirror table, that supports a reflected light guide mirror as the optical system, to scan a predetermined position on the platen glass, a document illumination module for controlling to illuminate the document, that moves along the surface of the platen glass, at a stop position of the mirror table, and an image scanning module for controlling to scan the image by the image scanning system from the document, which moves at the constant speed, at the stop position of the mirror table.
According to a preferred aspect of the present invention, the black stripe image detection module comprises a binarization module for controlling to binarize image data scanned by the image scanning module, an accumulation module for controlling to accumulate the binary data for a predetermined number of lines at N-line intervals (N: an arbitrary integer) in units of pixels, and a comparison module for comparing the accumulation result with a predetermined determination level, and controlling to determine that a black stripe image is generated at the corresponding pixel position when the accumulation result has exceeded the determination level.
According to a preferred aspect of the present invention, the black stripe image detection module comprises a black signal thickening module for controlling to select and output one with a smaller level of signals obtained before and after image data scanned by the image scanning module is delayed by a predetermined number of pixels in a main scan direction, a binarization module for controlling to binarize data output from the black signal thickening module, an accumulation module for controlling to accumulate the binary data for a predetermined number of lines at N-line intervals (N: an arbitrary integer) in units of pixels, and a comparison module for comparing the accumulation result with a predetermined determination level, and controlling to determine that a black stripe image is generated at the corresponding pixel position when the accumulation result has exceeded the determination level.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection module detects the presence/absence of generation of the black stripe image is set before a document scan by the image scanning module, and the presence/absence of generation of the black stripe image is detected by the black stripe image detection module using image data scanned at the predetermined position on the platen glass by the image scanning module while moving a belt surface of a document conveyor belt used in the document moving module by the control module.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection module detects the presence/absence of generation of the black stripe image is set after a document scan by the image scanning module, and the presence/absence of generation of the black stripe image is detected by the black stripe image detection module using image data scanned at the predetermined position on the platen glass by the image scanning module while moving a belt surface of a document conveyor belt used in the document moving module by the control module.
According to a preferred aspect of the present invention, a timing at which the black stripe image detection module detects the presence/absence of generation of the black stripe image is set between neighboring documents upon successively scanning documents by the image scanning module, and the presence/absence of generation of the black stripe image is detected by the black stripe image detection module using image data scanned at the predetermined position on the platen glass by the image scanning module while moving a belt surface of a document conveyor belt used in the document moving module by the control module.
According to a preferred aspect of the present invention, the program module further comprises a warning module for controlling to generate a warning message indicating that dust or soil is attached to the surface of the platen glass when the black stripe image detection module detects generation of the black stripe image.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.